Apparatus for sorting comestible and other objects



y 1968 M. c. HOOVER 3,382,975

APPARATUS FOR SORTING COMESTIBLE AND OTHER OBJECTS Filed Aug. 24, 1966 5 Sheets$heet 1 INVENTOR. MICHAEL C. HOOVER BY a ATTORNEY May 14, 1968 M. c. HOOVER APPARATUS FOR SORTING COMESTIBLE AND OTHER OBJECTS Filed Aug. 24, 1966 5 Sheets-Sheet 2 mun-wi l .I| Q rH t m P Q 9 A mm 6 L I i 'fla; NM A iyllHHlH 8 INVENTOR. MICHAEL C. HOOVER BY wk I ATTORNEY May 14, 1968 M. c. HOOVER APPARATUS FOR SORTING COMESTIBLE AND OTHER OBJECTS PDQPDO OPEIOQ PmOIm ATTORNEY y 14, 8 M. c. HOOVER 3,382,975

APPARATUS FOR SORTING COMESTIBLE AND OTHER OBJECTS I 5 Sheets-Sheet 4 SHORT POTATO |l2-| (DEFECTIVE) INVENTOR. MICHAEL C. HOOVER F I -7 BY mvffla ATTORNEY y 1968 M. c. HOOVER 3,382,975

APPARATUS FOR SORTING COMESTIBLE AND OTHER OBJECTS Filed Aug. 24, 1966 5 Sheets-Sheet 5 INVENTOR MICHAEL C. HOOVE R BY mmfez ATTORNEY United States Patent 3,382,975 APPARATUS FOR SORTING COMESTIBLE AND OTHER OBJECTS Michael C. Hoover, Houston, Tex., assignor to Mandrel Industries, Inc., Houston, Tex., a corporation of Michigan Filed Aug. 24, 1966, Ser. No. 574,664 16 Claims. (Cl. 209-73) This invention relates to processing apparatus for discrete objects such as, for example, fruits and vegetables, and particularly to apparatus for arranging and moving such objects serially past a detecting, inspecting or classifying means for counting, grading or sorting.

In the food processing art it is often desirable to sort objects, such as for example, peeled potatoes, in such a way that objects with imperfections are rejected. Since peeled potatoes are generally white and the imperfections thereof show up as dark spots, the sorting can be accomplished by passing the potatoes through a photo-electric device wherein the potatoes are illuminated and the presence of dark spots is observed and signalled to a rejection apparatus located further downstream on the path that is followed by the potatoes. For other vegetables and fruits, color sorting is desirable and can be accomplished with a modified form of the photoelectric device. Sorting by size, or even merely counting, can also be accomplished with appropriate modifications, and systems of this general class can be used for processing objects other than food, such as pearls or rocks.

An important requirement of all such systems employing photoelectric inspection devices is to maintain the output thereof in calibration with a precise reference value, so that the color or darkness of the objects is measured against an unvarying standard. Various influences may cause the photoelectric device to drift with time. If the objects are conveyed in a transparent fluid, the fluid may become contaminated and thus reduce light transmission. The illuminating lamp bulbs tend to decrease in output with age. If the photoelectric device contains a photomultiplier, the output may be unstable and the photomultiplier may vary in gain. The art therefore usually provides a normalizing device that automatically normalizes or re-calibrates the photoelectric device from time to time, and during periods when no object is being viewed.

The selection of the normalizing period is of some importance. For example, the art contains object conveying means such as wheels with spaced suction ferrules for picking up the objects and moving them rapidly past the inspection station. For maximum efficiency, the ferrules are spaced as closely as possible, so that often the objects are touching one another and there is no gap between for normalizing, save for random gaps occurring when an occasional ferrule for some reason fails to pickup one of the objects. However, the random occurrence of gaps should not be relied upon. It is therefore customary to manufacture such wheels with at least one blank ferrule, so that at least one normalizing period per revolution of the wheel will occur. Since the normalizing period is thus predetermined, very simple systems can be used to perform the normalizing function. Such a solution is not possible, however, with conveyors, such as belts or fluid conveyors, that move the objects in random spacing. In such machines, more complex arrangements must be made to ensure that normalizing takes place each and every time such random spacing occurs between objects.

Another requirement of all such systems is that the objects be moved through the inspection and rejection apparatus in serial order, preferably with substantial spaces between objects. Otherwise, if two objects of different classes (e.g., one perfect and the other imperfect) move "ice abreast through the inspection apparatus, they may both be classified and sorted as if they were the same. The perfect object may mask the defect of the other, and both are accepted; or if the defect is discerned, both objects are rejected.

Furthermore, there are occasional difficulties in making the ejection apparatus perform satisfactorily with objects, such as potatoes, that have different lengths. While potatoes can be easily graded and serialized (singulated) on the basis of their Widths or thicknesses, the variation in lengths as they pass the inspection device must still be taken into account. If the ejection device is a jet of pressurized air operated in predetermined time delay after the inspection operation, a short potato may be hit by the jet near its center of gravity, but a long potato may be hit elsewhere, causing it to cartw'neel and to be dam aged or improperly classified. Also, a long potato, having greater mass, may require a jet or jets exerting greater force to deflect such a potato to the same degree as a small potato, so that all rejected potatoes are accurately deflected to the same target bin.

Accordingly, it is an object of the present invention to provide a processing apparatus that normalizes itself each and every time an object departs from the viewing zone of the apparatus.

It is a further object of the invention to provide a processing apparatus that conveys and singulates objects with a minimum amount of damaging bumping and jostling.

It is a further object of the present invention to provide an apparatus suitable for accurate sorting of objects having different lengths.

These and other objects are accomplished in the present invention by placing the objects in a conveying fluid so that substantially all forces applied to the objects are applied only through the fluid medium, and direct jostling and bumping are avoided. Means are provided for moving the fluid containing the objects, and for arranging or singulating the objects in serial order; such means may take the form of a so-called solids pump, which pumps the fluid without bumping or crushing the objects, and at the same time singulates the objects. The fluid containing the objects is then passed through an inspection device that (l) detects the presence or absence of defacts, and (2) grades the objects according to size. Defect and size signals are then sent to an air-jet deflecting apparatus that can be operated in various modes depending 'on the size of the object. If the object is defective, it is deflected in a suitable mode. The fluid is then separated from the objects, and the deflected and non-deflected objects are collected in separate bins. A normalizing device is provided for normalizing the inspection device each time an object departs therefrom.

The invention will be described in greater detail with reference to the drawing, in which:

FIGURE 1 is a side elevation of a portion of an apparatus incorporating the invention;

FIGURE 2 is a plan view of the apparatus of FIG- URE 1;

FIGURE 3 is an elevation section taken along the plane of lines 3-3 of FIGURES 2 and 4;

FIGURE 4 is an elevation section taken along the plane of lines M of FIGURE 3;

FIGURE 5 is an elevation section taken along the lines 55 of FIGURE 4;

FIGURE 6 is a circuit diagram;

FIGURE 7 is a waveform diagram;

FIGURE 8 is an operational diagram;

FIGURE 9 is an enlarged broken-away elevation view of a portion of the apparatus taken along the plane of lines 9--9 of FIGURE 1; and

FIGURE 10 is a sectional plan view taken along the lines 10'10 of FIGURE 9.

Referring now to the drawings, and particularly to FIGURE 1 thereof, there is shown a processing apparatus ilor sorting, for example, peeled potatoes. The potatoes '1 1 are inserted into a hopper 12, which tapers downward into a water tank 13 and is coupled to the inner opening of a tank outlet 14. The hop-per 12 has at least one opening 16 smaller than any of the potatoes, these openings being located below the level of the water 17 in the tank, so that the potatoes and water are mixed inside the hopper for conveying the potatoes through the outlet 14. A solids pump 18 is coupled to the outlet 14 for moving the conveying water containing the potatoes. The pump illustrated is of standard commercial manufacture, and consists of a centrifugal pump having a central intake 19 and a peripheral outlet 21. The outlet 14, intake 19 and outlet 21 are all of inside diameter sufficiently great to pass more than one potato abreast, so as not to cause jamming of the potatoes. It has been found in practice, however, that a pump of the type illustrated has the elfect of singulating the potatoes as they pass through, even if they enter abreast. Accordingly, at the outlet 21, a conduit 22 is provided, tapering to an inside diameter barely great enough to pass one otato at a time, so that the potatoes, once singulated, remain in serial order. It will be understood that other pumping or singulating means, either known or at present unknown in the art, may be used.

The conduit 22 is formed with a horizontal transparent segment 23 for visual inspection of the fluid and potatoes, and continues to an inspection device 24, which may be mounted on hangars 26 above the tank 13. A box 27, containing various electronic circuits, is mounted on the side of the tank 13. The inspection device 24 examines the potatoes for defects and makes a determination whether or not to deflect the potato from a predetermined path 28 as the potato emerges from the inspection device 24. A pair of air jet means 31, 32 is provided for such deflection. As shown in FIGURE 2, the unblemished potatoes proceed in a straight vertical plane directly to a horizontal screen 33, which is mounted above the tank 13, so that the conveying water falls through and is returned to the tank, and only the potatoes are caught. The potatoes, impelled by the pump 18, have an appreciable momentum as they leave the viewing device 24, and roll along the screen 33 to a ramp 34, and down the ramp to a conveying means, such as conveying belt 36. To separate the blemished potatoes, the air jet means 31, 32 are mounted to deliver horizontal jets of air transverse to the path 28, so that the blemished potatoes, upon operation of the air jets, are deflected ten or fifteen degrees to another part of the screen 33. A partition 37 is mounted along the length of the screen 33, the ramp 34, and the belt 36, to keep separate the deflected and non-deflected potatoes. Bin sides 38 and "a water splash guard 39 are also provided.

It will be noted that the first air jet means 31 is positioned closest to the viewing device 24 and at a predetermined distance therefrom, and the second air jet means 32 is positioned more remote from the viewing device 24. The operation of these jet means, either singly or in tandem, provides an advantageous flexibility in dealing with potatoes of varying sizes, as will be later explained.

The structure of the viewing means 24 is shown in FIGURES 3-5. The means is enclosed in a cylindrical housing 41, along the axis of which runs a transparent tube 42 communicating with the conduit 22, 23. As the water borne potatoes pass through the transparent tube 42, they also pass through an interior cylindrical housing 43, which surrounds a midportion of the tube 42 and encloses a viewing zone 44. Also enclosing the viewing zone is a transparent fluid jacket 46 filled with water, so that a potato that encounters the wall of the tube 42 will have the same appearance, from outside the jacket 46, as it would if it did not encounter the wall of tube '42.

To illuminate the potatoes in the viewing zone, there are provided two rings of lamps 47, mounted so as to project into the interior housing 43 at the end walls thereof. In effect, the two rings of lamps are spaced upstream and downstream from the viewing zone so as to illuminate the ends of the potatoes as well as the midportions, and also so as not to shine directly into the ends of a plurality of viewing tubes 48 that are ar ranged in a plane normal to the axis of tube 42 at the midsection of the viewing zone. The viewing tubes 48 are aligned with their axes on diameters of the tube 42 and are circumferentially equi-spaced. Diame'trica-lly opposite the inner end of each viewing tube, on the interior wall of housing 43, is mounted a background element 49, consisting of a card or plate having predetermined color and reflectance characteristics so as to serve as an optical standard or reference against which the color and reflectance of each potato may be measured, and also to serve as a standard for the normalizing of the viewing apparatus. Except for the areas covered by the background elements 49, the interior wall of the housing 43 is painted fiat white.-

Since each. viewing tube 48 must look along a diameter of tube 42 directly at one of the background elements 49, and not into the end of another viewing tube, it follows that there must be an odd number of viewing tubes and an odd number of background elements; in the illustrated case, nine each.

Each of the viewing tubes 48 contains an objective lens 51, an optical frame element 52, a detocusing lens system 53, an optical filter 54, and a photomultiplier tube 57, all standard in the art. The interior surface of each viewing tube is roughened, corrugated, or screw-threaded, and is painted black to reduce reflection. To make the best use of the space within housing 41, each tube 48 is bent at right angles between the lens 53 and filter 54, and a 45- degree mirror 58 is provided for transmitting the received light to the filter.

The elements 51-58 are arranged in a well-known manner to provide a signal from the photo-multiplier 57, of which signal the amplitude varies in proportion to the darkness (below that of element 49) of the reflected light from each potato. Thus unblemished white potatoes produce no signal or an insignificant one, while potatoes with black rot spots produce a significant deflecting signal.

As shown in the drawing, the elements so far described within housing 41 are mounted by connection with the housing and with a plate 61, which is positioned by hangars or spacers 62, 63 from the end walls of the housing. Also mounted on the plate 61 are an odd number of object detectors 66, 67, which are used to detect the presence or absence of potatoes in the viewing zone 44. Each object detector comprises a light source assembly 66 and a diametrically opposite photoelectric assembly 67, and the intermediate diameter on which each corresponding pair of elements 66, 67 is aligned is angularly spaced from all diameters occupied by the viewing tubes 48 and background elements 49.

Each light source assembly 66 includes first and second light sources 68, 69. The first light source 68 emits a beam of light directed parallel to the corresponding The significance of the object detectors, and their abovementioned signals from photodiodes 71, 72, lies in their use for controlling the novel normalizing arrangement of the present invention, and their use as well for supplementing the action of the blemish detecting viewing tubes 48, particularly in precisely delaying the deflection signal to the air jet means 31, 32, and in operating the air jet means in a flexible variety of modes that is suitable to the handling of potatoes of varying sizes. As will be seen, for both of these purposes, it is desirable to know precisely when a potato enters the viewing zone 44 and precisely when the potato leaves the zone, and this knowledge is important at least for normalizing whether or not the potato has a blemish. Consequently the viewing tubes 48, which produce signals only for blemished potatoes and even then not usually in relation to the precise times of entry and exit of the potato in the viewing zone, cannot be relied upon to furnish this desired information, and means such as the object detectors are needed.

As shown in FIGURES 6 and 7 the signals from the photodiodes 71, 72 are a pair of first and second gating pulses 81, 82. The pulse 81 from lead photodiode 71 begins when a potato enters the viewing zone, and the pulse 82 from lag photodiode 72 ends when the potato leaves the viewing zone. These pulses are both received by a NOR gate 83, which emits a third gating pulse 84 beginning with the beginning of pulse 81 and ending with the end of pulse 82. The pulse 84 is received by a normallyclosed normalizer switch 86 and storage capacitor 87, and the switch is opened for the duration of the pulse 84. The

' switch is connected in a closed series feedback loop with a control element 88, the dynode of the photomultiplier 57, and an adjustable voltage detector 89 that will change its state when the photomultiplier output voltage exceeds a predetermined value. When no article is in view, the photomultipliers look through the tube 42 full of liquid at the colored standard 49. The reflectance of this standard is chosen to be the same as the darkest good product. Anything that is darker than this standard can be considered defective and will be ejected.

As previously mentioned, various things cause the output of the photomultiplier to fluctuate or drift with time. The liquid can become contaminated and thus reduce light transmission. The lamp bulbs slowly decrease in output with age. Some photomultipliers are unstable and thus vary in gain. The gain of a photomultiplier is an exponential function of the dynode supply voltage, therefore a small change in dynode voltage will produce a large change in gain. The control element 88 is placed in series with the dynode supply. This control element is activated by the output of the photomultiplier. Thus, if the loop gain of the system is high enough, the control element will maintain photomultiplier output constant. The normalizer switch 86 shown on the block diagram is a solid state switch with a storage capacitor 87. The switch is normally closed, thus closing the feedback loop. When the control gating circuit 71-72 sees an article come into view, it opens the switch to open the feedback loop. The storage capacitor holds the input to the control element 88 (called the Normalizer AGC Amplifier on the block diagram) constant while the switch is open. The switch is again closed after the article is passed out of view. If no'drift accurs while the article is in view, the photomultiplier output -will represent the true reflectance of the article relative to the color standard.

The voltage detector or output classifier '89 is a silicon controlled switch with the cathode gate connected to the photomultiplier amplifier and the anode gate connected to the control gating system. The cathode is connected to a variable voltage source and is set so that the photomultiplier amplifier output is just below the turn on voltage of the SCS when no article is in view. Thus an article that is slightly darker than the color standard will turn the SOS on. When the article goes out of view, the control gating circuit will turn the S68 oflf. A

6 visual indicator 91 is connected to the SOS so that the operation of each viewing channel can be monitored.

As will be understood, therefore, the normalizing circuit is operated whenever the viewing zone is completely clear of potatoes. Since the viewing zone is comparatively narrow, the potatoes must be very closely spaced in order to prevent the operation of the normalize-r between each and every potato. The natural action of the pump 18 is to space the potatoes substantially equidistantly, and since the dimension of this spacing can be controlled by varying the pumping rate and the rate of potato input, it is possible to arrange the system in such a way that normalizing is almost never prevented.

When the normalizerswitch 86 is open, as when a potato is passing through the viewing zone, the photomultiplier 48 emits a signal 92 that has a reference level amplitude 93 corresponding to a vie-w of the background element 49 alone, and a varying amplitude 94 corresponding to a view of a photo. When the amplitude of this signal exceeds a predetermined threshold level 96, corresponding with the presence of a blemish, the SCS 89 begins emitting a continuing stored rejection pulse 97. All of the viewing assembly channels are coupled in parallel to an OR gate 98, so that any of the pulses 97 are sufiicient to provide an output from the OR gate 98. Such output consists of a rejection initiating pulse 101 of predetermined time duration beginning at the end of pulse 97. Since it is desirable that the pulse 101 be emitted only just as the potato leaves the viewing zone, in order to establish the beginning of the time delay ending in operation of air jets uniformly for each potato, a first reset means 102 is coupled to receive pulse 82 from lag photodiode 72 and to provide a spike pulse 103 to the voltage detector 89, so as to end the pulse 97 coincident with the end of pulse 82, causing initiation of the pulse 101. Naturally, if there is no blemish on the potato, no pulse 101 is emitted. If there is a blemish, pulse 101 is sent to a delay circuit comprising a delay line 104 consisting of a number of multivibrators emitting pulses 106, 107 and 108, an ejector dwell device 109 emitting a pulse 110 for establishing the time duration of the air jet, and a drive amplifier 1'11 emitting a first deflection actuating pulse 112 to the air jet means for operating same.

The circuits above described are suflicient for operating the apparatus if no account is to be taken of the size of the potatoes. However, when, as is usually desirable, such a distinction is to be made, an AND gate 113, emitting a pulse 115, is inserted between the OR gate 98 and the delay line 104. This delay means is then used for short potatoes, and a second delay means for long potatoes, consisting of an AND gate 114, delay line 116, ejector dwell 117, and drive amplifier 118 is coupled to OR gate 98. The pulse 101 will help to operate either delay means, but the section of which is actually to be operated requires a second input to the appropriate AND gate 113 or 114 from a potato size sensing means described as follows.

To sense the size or length of the potato, an integrating and object size signalling means 116 is coupled to receive the lead photodiode pulse 81 and to emit a continuing pulse 117, the amplitude of which varies as the width of the first gating pulse 81. At the end of pulse 81, pulse 117 continues at its maximum attained amplitude, which of course is a function of the length of the potato. The means 116 also includes means for receiving the pulse 117 and for emitting .a continuing large-object pulse 118 beginning when the pulse 117 exceeds a predetermined amplitude 119, and a continuing small-object pulse 121 whenever there is no pulse 118.

It is important, however, to end the pulse 118 in such a way that it outlasts the pulses 82, 84 so that there will be coincidence of the pulses 118 and 101 in the gate 114. A second reset means 122 is therefore coupled to the lag photodiode 72 to receive the pulse 82 therefrom and to emit a pulse 123 of predetermined time duration beginning with the end of pulse 82; and the means 122 is coupled to an input of means 116 so as to perpetuate pulse 118 to the end of pulse 123. Pulse 118 is sent to gate 114, and if at the end of the viewing function there is also a pulse 101 at the gate 114, the long potato delay line is actuated. If there is a pulse 101 and no pulse 118, then there will be a pulse 121, and the short potato delay line is actuated. Such actuation causes AND gate pulse 125, multivibrator pulses 126, 127 and 128, an ejector dwell pulse 129, and a second actuating pulse 131 for operating the air jets.

Various methods of operating the air jets are illustrated in FIGURE 8. For short potatoes, the amplifier 111 may be coupled to operate jet 31 alone just as the center of gravity of the potato arrives at the jet, the time delay 136 being established by setting the delay line 104 in conjunction with the known velocity of the potato and the known distance between the photodiode 72 and the jet 31. Care must be taken to ensure that the jet 31 is spaced from the end of tube 42 sufficiently far that the trailing end of the potato has cleared the tube end when the center of gravity of the potato is at the jet. The delay line 116 may also be set to produce the same time delay 136, and the amplifier 118 coupled to operate the jet 32 alone, so that a long potato 137 will also be struck at its center of gravity by the single jet 32. Alternatively, both jets may be operated simultaneously after time delay 136, by either or both delay circuits. However, such a mode is usually not preferable since a long potato 138 will thus usually be struck above its center of gravity, and in the case of a small potato 139, there may be another non-defective small potato 141 .in position to be deflected by jet 32. A further preferable mode is to couple amplifier 111 to operate a jet 31 alone with time delay 136 for small potatoes, and amplifier 118 to operate both jets 31, 32 after a shorter time delay 145 for long potatoes 146. Thus the long potatoes are struck with greater force by both jets, equidistantly from the center of gravity of the potato.

The construction of the air jet means 31, 32 is shown in FIGURES 9 and 10. The two means are identical, and only one is shown. The means comprises a housing 148 having a curved surface 149 shaped to conform to the envelope of the path of the potatoes, and enclosing a number of tapered channels 151 opening onto the surface 149. Each of the channels 151 has a perforated nozzle 152 inset in the end of the channel remote from the surface 149. Each nozzle 152 is covered by a light magnetically permeable valve disk 153, which is normally held against the nozzle 152 by pressure of compressed air in a plenum chamber 154. The chamber 154 is supplied from a conduit 156. When it is desired to open the valves, a number of electromagnetic coils 157 are energized so as to attract the disks 153 and uncover the perforations of the nozzles 152. The disks 153 are substantially imprisoned between the nozzles and coils, and while the disks have a limited range of movement, they cannot escape.

It will be understood that many alternative circuit and other elements may be used to perform the functions described above, without departing from the spirit of the invention as claimed below. For example, it will be apparent that the detecting apparatus 71, 72, 83 may be operated independently of the classifying and deflection apparatus to provide a counting system merely for counting the number of potatoes that pass through the viewing zone, and many other arrangements are possible.

Thus there has been described a device in which objects are placed in a conveying fluid so that substantially all forces applied to the objects are applied only through the fluid medium, and direct jostling and bumping are avoided. Means are provided for moving the fluid containing the objects, and for arranging or singulating the objects in serial order; such means may take the form of a so-called solids pump, which pumps the fluid without bumping or crushing the objects, and at the same time singulates the objects. The fluid containing the objects is then passed through an inspection device that (l) detects the presence or absence of defects, and (2) grades the objects according to size. Defect and size signals are then sent to an air-jet deflecting apparatus that can be operated in various modes depending on the size of the object. If the object is defective, it is deflected in a suitable mode. The fluid is then separated from the objects, and the deflected and non-deflected objects are collected in separate bins. A normalizing device is provided for normalizing the inspection device each time an object departs therefrom.

What is claimed is:

1. An apparatus for processing a plurality of objects,

comprising:

means for moving said objects on a predetermined path through a predetermined viewing zone in serial order, and at a predetermined velocity;

means for viewing said objects at said viewing zone and for producing a deflecting signal in response to passage of objects having a predetermined characteristic;

means downstream on said path from said viewing zone for receiving said deflecting signal and for thereupon deflecting the corresponding object from said path;

means for detecting the departure of an object from said viewing zone and for causing said deflecting sig nal to be transmitted to said deflecting means; and

means for normalizing said viewing means, said normalizing means being coupled to said detecting means for causing said normalizing each time one of said objects departs from said viewing zone.

2. An apparatus as recited in claim 1, wherein said means for moving said objects includes:

a transparent fluid for transporting said objects, and conduit means therefor having means for inserting said objects into said conduit and fluid;

means coupled to said conduit for moving said fluid and the objects carried thereby, and for causing said objects to be singulated so as to move in spaced-apart serial order in said conduit.

3. An apparatus as recited in claim 2, wherein said detecting means includes:

an odd number of object-detectors positioned at said viewing zone and sensitive to the passage of said objects for emitting a first electrical gating pulse beginning when one of said objects enters said viewing zone, and a second electrical gating pulse ending when said object leaves said viewing zone.

4. An apparatus as recited in claim 3 wherein said viewing means includes:

a transparent tube coupled to said conduit for receiving and passing said fluid and objects, said tube having a midsection segment defining said viewing zone, and at least said viewing zone portion of said transparent tube being provided with an exterior transparent fluid jacket filled with said fluid;

a plurality of light sources arranged circumferentially around said tube and spaced therefrom, both upstream and downstream from said viewing zone;

an odd number of viewing tubes arranged in a plane normal to the axis of said transparent tube and passing through said viewing zone, said viewing tubes being circumferentially equispaced about and pointing toward said axis, the interior of each tube being substantially masked from said light sources;

an odd number of background elements having predetermined color and reflectance characteristics and each positioned diametrically opposite one of said viewing tubes on the opposite side of said transparent tube; and

means mounted at least partly within said viewing tubes for receiving reflected light from each of said objects as said object passes through said viewing zone, said last-named means being responsive to said reflected light to produce said deflecting signal when said object has said predetermined characteristic.

5. An apparatus as recited in claim 4 wherein each of said object detectors includes:

a light source assembly aligned on an intermediate diameter of said tube that is angularly spaced from all diameters occupied by said viewing tubes and background elements, said light source assembly containing first and second light sources, said first light source emitting a beam of light directed parallel to said intermediate diameter at the upstream end of said viewing zone, and said second light source emitting a beam of light directed parallel to said intermediate diameter at the downstream end of said viewing zone;

a photoelectric assembly diametrically opposite said light source assembly and containing first and second photoelectric devices for receiving said respective light beams in the absence of said objects, and for emitting said first and second gating pulses when said light beams are interrupted; and

means for receiving said first and second gating pulses and for emitting a third gating pulse beginning with the beginning of said first gating pulse and ending with the end of said second gating pulse.

6. An apparatus as recited in claim 5 wherein said viewing tube light-receiving and deflecting-signal-emitting means includes:

photoelectric means for emitting a signal of reference level amplitude when said background elements alone are viewed thereby, and a signal of amplitude varying from said reference level when any portion of one of said objects passing through said viewing zone has color and reflectance characteristics varying correspondingly from said characteristics of said background elements, and means coupled to said photoelectric means for emitting a continuing stored rejection pulse beginning when said varying-amplitude signal exceeds a predetermined amplitude;

first reset means coupled to said second photoelectric device and to said rejection-pulse-emitting means for ending said stored rejection pulse at the end of said second gating pulse;

means coupled to said stored-rejection-pulse-emitting means for emitting a rejection-initiating pulse of predetermined time duration when said stored rejection pulse ends; and

said normalizing means including feedback circuit I means for maintaining said reference level signal precisely and continuously at said reference level when no object is in said viewing zone, said circuit including a normally-closed normalizer switch and means coupled to said switch and said third gating pulse means for opening said switch while said third gating pulse is being emitted.

7. An apparatus as recited in claim 6 and also including:

integrating and object size signaling means coupled to said first photoelectric device for receiving said first gating pulse and for emitting a continuing signal the amplitude of which varies as a function of first gating pulse width and the size of the stimulating object;

said integrating and object size signaling means also including means for receiving said size-varyingamplitude signal and for emitting a continuing largeobject pulse beginning when said size-varying-amplitude signal exceeds a predetermined amplitude, and a continuing small-object pulse whenever there is no large-object pulse; and

second reset means coupled to said second photoelectric device and to said integrating and object size signaling means for ending said size-varyiug-ampli- 10 tude signal and said large-object pulse in predetermined time delay after the end of said second gating pulse. 8. An apparatus as recited in claim 7 and also including small-object delay means coupled to said rejectioninitiating pulse means and to said integrating-andobject-size signalling means for receiving said rejection initiating pulse and said large object pulse and for producng a first deflection actuating pulse when said rejection initiating pulse and said small-object pulse occur in temporal coincidence, said first actuating pulse being emitted in first predetermined time delay after the beginning of said coincidence; and

large-object delay means coupled to said rejectioninitiating pulse means and to said integrating-andobject-size signalling means for receiving said rejection initiating pulse and said large object pulse and for producing a second deflection actuating pulse when said rejection initiating pulse and said largeobject pulse occur in temporal coincidence, said second actuating pulse being emitted in second predetermined time delay after the beginning of said last-named coincidence.

9. An apparatus as recited in claim 8 wherein said deflecting means includes:

at least a pair of pressurized air jet means of which a first is positioned at a predetermined spacing and the second is positioned at a greater spacing from the downstream end of said transparent tube, both of said air jet means being oriented to direct parallel jets of air transverse to said path for deflecting said objects therefrom; and

each of said jet means having valve means selectively operable to release and to shut off said jet thereof.

10. An apparatus as recited in claim 9 wherein:

means are coupled to said small-object delay means for receiving said first deflection actuating pulse therefrom and for thereupon causing at least said first air jet means to release said jet thereof;

the spacing of said air jet means from the downstream end of said transparent tube having a predetermined relation to said first time delay and to said predetermined object velocity such that the jet of said first air jet means is released after the stimulating object has cleared said end of said tube and substantially at the instant of arrival of the center of gravity of such a stimulating object having a size falling within a predetermined small size range.

11. An apparatus as recited in claim 10 wherein:

means are coupled to said large-object delay means for receiving said second deflection actuating pulse therefrom and for thereupon causing at least said second air jet means to release said jet thereof;

the spacing of said air jet means from the downstream end of said transparent tube having a predetermined relation to said second time delay and to said predetermined object velocity such that the jet of said second air jet means is released after the stimulating object has cleared said end of said tube and substantially at the instant of arrival of the center of gravity of such a stimulating object having a size greater than the upper limit of said predetermined small size range.

12. An apparatus as recited in claim 10 wherein:

means are coupled to said large-object delay means for receiving said second deflection actuating pulse therefrom and for thereupon causing both said first and second air jet means to release said jets thereof;

the spacing of said air jet means from the downstream end of said transparent tube having a predetermined relation to said second time delay and to said predetermined object velocity such that the jets of said first and second air jet means are released after the stimulating object has cleared said end of said tube and substantially at the instant of arrival, equidistant between said jets, of the center of gravity of such a stimulating object having a size greater than the upper limit of said predetermined small size range. 13. An apparatus as recited in claim 2 wherein said conduit and inserting means include:

a tank containing said fluid and having an outlet port; a hopper mounted on the interior of said tank, said hopper having an Open top above the level of fluid in said tank and an outlet at the bottom thereof coupled to said outlet port of said tank on the interior thereof; said hopper also having at least one opening smaller than any of said objects and positioned below the fluid level of said tank for admitting said fluid to said hopper and to said outlet port; and whereby said objects may be fed into said hopper for mixing with said fluid, and said mixed objects and fluid pass together through said outlet port and out of said tank. 14. An apparatus as recited in claim 13 wherein said moving and singulating means includes:

a solids pump coupled to said tank outlet port; said conduit means also including a conduit pipe leading from the outlet of said pump to said viewing means. 15. An apparatus as recited in claim 14 and also including:

screen means positioned above said tank so as to receive both deflected and non-deflected objects coming from said viewing means, while passing the transporting fluid for return to said tank, and a partition dividing said screen means into separate portions so as to keep said deflected objects separate from the non-deflected objects: and conveyor means for separately receiving and removing said deflected and non-deflected objects from said screen means. 16. As a subcombination, an apparatus for processing a plurality of objects, comprising:

means for moving said objects on a predetermined path through a predetermined viewing zone in serial order, and at a predetermined velocity;

said moving means including a fluid for transporting said objects and conduit means therefor having means for inserting said objects into said conduit and fluid;

said moving means also including means coupled to said conduit for moving said fluid and the objects carried thereby, and for causing said objects to be singulated so as to move in spaced-apart serial order in said conduit;

means for detecting the presence of an object in said viewing zone, including a light source assembly aligned on a diameter of said tube, said light source assembly containing first and second light sources, said first light source emitting a beam of light directed parallel to said diameter at the upstream end of said viewing zone, and said second light source emitting a beam of light directed parallel to said diameter at the downstream end of said viewing zone;

said detecting means also including a photoelectric assembly diametrically opposite said light source assembly and containing first and second photoelectric devices for receiving said respective light beams in the absence of said objects, and for emitting respective first and second gating pulses when said light beams are interrupted; and

said detecting means also including means for receiving said first and second gating pulses and for emit ting a third gating pulse beginning with the beginning of said first gating pulse and ending with the end of said second gating pulse.

References Cited UNITED STATES PATENTS 2,690,258 9/1954 Cox 250223 X 2,803,754 8/1957 Cox 250-223 X 2,803,756 8/1957 Cox 250-223 X 2,841,718 7/1958 Hoover 250-223 X 2,966,264 12/1960 Cox 250223 X 3,066,797 12/1962 Fraenkel 209111.6

ALLEN N. KNOWLES, Primary Examiner. 

1. AN APPARATUS FOR PROCESSING A PLURALITY OF OBJECTS, COMPRISING: MEANS FOR MOVING SAID OBJECTS ON A PREDETERMINED PATH THROUGH A PREDETERMINED VIEWING ZONE IN SERIAL ORDER, AND AT A PREDETERMINED VELOCITY; MEANS FOR VIEWING SAID OBJECTS AT SAID VIEWING ZONE AND FOR PRODUCING A DEFLECTING SIGNAL IN RESPONSE TO PASSAGE OF OBJECTS HAVING A PREDETERMINED CHARACTERISTIC; MEANS DOWNSTREAM ON SAID PATH FROM SAID VIEWING ZONE FOR RECEIVING SAID DEFLECTING SIGNAL AND FOR THEREUPON DEFLECTING THE CORRESPONDING OBJECT FROM SAID PATH; MEANS FOR DETECTING THE DEPARTURE OF AN OBJECT FROM SAID VIEWING ZONE AND FOR CAUSING SAID DEFLECTING SIGNAL TO BE TRANSMITTED TO SAID DEFLECTING MEANS; AND MEANS FOR NORMALIZING SAID VIEWING MEANS, SAID NORMALIZING MEANS BEING COUPLED TO SAID DETECTING MEANS FOR CAUSING SAID NORMALIZING EACH TIME ONE OF SAID OBJECTS DEPARTS FROM SAID VIEWING ZONE. 